GPT-5.3 Codex vs Qwen3.8-Flash-Next
GPT-5.3 Codex 
Qwen3.8-Flash-Next Verdict
- GPT-5.3 Codex (xhigh) leads on quality: 65.4 vs 61.6.
- GPT-5.3 Codex (xhigh) is stronger in agents & tools, composite, instruction following, knowledge, long context, reasoning.
- Qwen3.8-Flash-Next is stronger in coding, multimodal.
- Qwen3.8-Flash-Next is 21× cheaper ($0.230 vs $4.81 per 1M blended).
- GPT-5.3 Codex (xhigh) streams 2.2× faster (125 vs 55 tokens per second).
| Metric | GPT-5.3 Codex (xhigh) | Qwen3.8-Flash-Next |
|---|---|---|
| BenchLeader Index | 65.4 | 61.6 |
| Agents & tools score | 79.8 | 65.8 |
| Coding score | 61.7 | 71.2 |
| Composite score | 70.2 | 67.4 |
| Instruction following score | 73.4 | – |
| Knowledge score | 69.4 | 59.6 |
| Long context score | 68.2 | 66.3 |
| Multimodal score | 63.0 | 64.3 |
| Reasoning score | 74.4 | 63.4 |
| Blended price $/M | $4.81 | $0.230 |
| Output speed | 125 tok/s | 55 tok/s |
| Time to first answer | 50.8 s | 39.0 s |
| Context window | 400k | 256k |
| WeirdML | 77.9% | – |
| LMArena WebDev | – | 1635 |
| LMArena Agent | – | -0.1 |
| LiveBench | – | 76.2% |
| LiveBench Reasoning | – | 87.4% |
| LiveBench Coding | – | 72.5% |
| LiveBench Agentic Coding | – | 61.6% |
| LiveBench Mathematics | – | 85.8% |
| LiveBench Data Analysis | – | 74.2% |
| LiveBench Language | – | 74.6% |
| LiveBench Instruction Following | – | 77.1% |
| AA Intelligence Index | 32.5 | 39.9 |
| IFBench | 75.4% | – |
| AA-LCR | 83.3% | 79.7% |
| MMMU-Pro | 78.5% | 79.8% |
| AA-Omniscience | 10.9 | -9.7 |
| Terminal-Bench Hard | 53.0% | – |
| GPQA Diamond (AA) | 91.5% | 92.3% |
| Humanity's Last Exam (AA) | 42.5% | 38.0% |
| SciCode (AA) | – | 50.6% |
| τ²-Bench Telecom (AA) | 86.0% | – |
| LiveCodeBench | 87.3% | – |
| IOI | 53.8% | – |
| SWE-bench (Vals) | 78.0% | – |
| CritPt | 16.9% | 11.1% |
| GDPval (AA) | – | 57.4% |
| τ²-Bench Banking (AA) | – | 45.4% |
| Vibe Code Bench v1.1 | 61.8% | – |
| ALE-Bench | 1655.2 | – |
Data as of 2026-09-19. Best configuration of each model; every score links to its source on the model pages.
GPT-5.3 Codex vs Qwen3.8-Flash-Next: questions
- Is GPT-5.3 Codex better than Qwen3.8-Flash-Next?
- GPT-5.3 Codex (xhigh) leads on quality: 65.4 vs 61.6. The BenchLeader Index combines every independent quality benchmark; GPT-5.3 Codex (xhigh) is ahead overall as of 2026-09-19, but check the category scores for your use.
- Is GPT-5.3 Codex better than Qwen3.8-Flash-Next for coding?
- Qwen3.8-Flash-Next scores higher in coding (71 vs 62 on the category index, where 50 is average).
- Is GPT-5.3 Codex better than Qwen3.8-Flash-Next for agentic tasks?
- GPT-5.3 Codex scores higher in agentic tasks (80 vs 66 on the category index, where 50 is average).
- Which is cheaper, GPT-5.3 Codex or Qwen3.8-Flash-Next?
- Qwen3.8-Flash-Next is cheaper: $0.230 against $4.81 per million tokens, blended at three input tokens per output token.
- Which is faster, GPT-5.3 Codex or Qwen3.8-Flash-Next?
- GPT-5.3 Codex streams faster: 125 against 55 output tokens per second.
- Which has the larger context window?
- GPT-5.3 Codex accepts more context: 400k against 256k tokens.